What is a bitcoin node?

A bitcoin node is a computer running software that checks every transaction and block against Bitcoin's rules, then relays valid data to other nodes on the network. It matters because nodes, not miners, decide what counts as valid bitcoin. Running one lets you verify your own balance and transactions without trusting a company or exchange to tell you the truth.

The most common setup is a "full node," like Bitcoin Core, which downloads the entire blockchain (over 600GB as of 2024) and independently checks each block's rules before accepting it. Miners propose blocks, but if a block breaks the rules, nodes reject it regardless of how much mining power backed it. Anyone can run a node on a home computer or a small device like a Raspberry Pi, and thousands of volunteers do, which is what keeps Bitcoin decentralized rather than controlled by a handful of large players.